It is hard to anticipate what the FAA will do since their decisions are partly political and partly pragmatic. It's very difficult to deal with a regulatory environment this, so I feel we should keep our scrutiny to the problem space that we can control and need to get permission for. After a disaster, a balloon pilot is definitely accepting a higher lever of risk when flying. For we non-balloon pilots, this is representative of the current risk they accept when flying on a good day specifically since they have limited maneuverability.
At the core of our dilemma is that in the event of a collision, public opinion will side with the hot-air balloon and blame the dumb robot aircraft, not matter how much the dumb robot did to avoid the collision........In spite of the fact that balloon flight direction is unpredictable.
From what I see so far, the existing operating principle for cases like these (manned balloon aircraft and drones) is summarized by:
"If you see me, don't hit me".....because they don't have positive control over their position and direction.
These videos hopefully bring light to the plight of balloons:
(How to control)
Another way to explain this operating principle is "Yield to the least maneuverable aircraft" unless you are the government, which is not required to conform to this rule. (this is similar to boating)
We should emphasize that with ADS-B, the current risk that balloons face is reduced since we all know where the balloons are now and can avoid collisions. Also, balloons need weather to navigate. ADS-B gives you weather data for free.
I've reached out to some of my commercial aviation friends to get more insight and I'll share what I learn.
The hot air balloon case is is hardest to solve so I'll start with that. A guy in an ultralight has a little more control and thus more responsibility. Balloons run into balloons already and that hasn't changed the operating guidelines thus far.
P.S. Here is short video for others who don't like reading my long paragraphs.